MetaWhere with jQGrid multisearch

if params[:_search] == "true" && params[:filters].present?
      filters = Hash.new
      j = JSON.parse(params[:filters])


       i=0
    	 until j.fetch("rules").size == i
      	  k = j.fetch("rules").to_a[i].values_at("field", "op", "data", "groupOp")
          if k[1] == "cn"
            k[1] = "matches"
            k[2] = k[2]+"%"
          elsif k[1] == "ge"
            k[1] = "gte"
          elsif k[1] == "le"
            k[1] = "lte"
          end

          if k[3] == "AND"
            k[3] = "&"
          elsif k[3] == "OR"
            k[3] = "|"
          end

          filters[("#{k[0]}").to_sym.send(("#{k[1]}").to_sym)] = "#{k[2]}"
        i += 1
       end